Instantaneous type time compressors and expanders for pulse time modulation transmission systems



NOV. 8, 1960 HUFNAGEL 2,959,641

1 INSTANTANEOUS' TYPE TIME COMPRESSORS AND EXPANDERS FOR PULSE TIMEMODULATION TRANSMISSION SYSTEMS Filed Jan. 2, 1957 2 Sheets-Sheet 1 BASE 6950. GEM

g E 3 W A '2 g 7 mAMs: l l l I I I l a g m x 1 our J 8.1? ,1, l //v REC.MARKER smamm AUDIO wAo J6 4a a S k 9 Q l6 16.5 4.; l 3 3 q 46 6cInventor R085?! 5. Ara/M4 6,22

Agent United States Patent INSTANTANEOUS TYPE TIME COMPRESSORS ANDEXPANDERS FOR PULSE TIME MODULA- TION TRANSMISSION SYSTEMS Robert ErnstHufnagel, Pompton Plains, N .J., assignor to International Telephone andTelegraph Corporation, Nutley, N.J., a corporation of Maryland FiledJan. 2, 1957, Ser. No. 632,241

15 Claims. (Cl. 179-15) This invention relates to message transmissionsystems, and more especially it relates to improved compressors andexpanders for such systems of the pulse time modulation kind,hereinafter referred to as PTM systems.

As is well known, for many reasons, it is desirable in certain kinds oftransmission systems to employ socalled compandor combinations. Suchcompandors comprise a volume compressor at the transmitter and acomplementary expander at the receiver. Various forms of such compandorshave been proposed heretofore for different kinds of transmission, forexample transmission of amplitude modulation, by frequency modulation,by pulse count modulation, and the like. However, the present inventionis directed primarily to a novel and improved instantaneous typecompandor for systems employing the principle of pulse time modulation.In such systems the transmission of intelligence is effected bytranslating the originating audio frequency signals, such for example asvoice frequency signals, into sampled time pulses whose time position ischanged to represent the wave shape of the audio frequency signalenvelope. Such a system is Well suited to multiplex transmission sinceit is possible to interleave the PTM pulses so as more efficiently andreliably to operate over radio frequency transmission links and thelike. However, with such PTM systems special problems arise which renderthe usual compandor arrangement not always satisfactory.

Accordingly, one of the principal objects of this invention is toprovide a compressor device and also an expander device which arespecially well suited for use in PTM systems. 7

A feature of the invention relates to an instantaneous type compressoror to an instantaneous type expander wherein the compression orexpanding function is controlled by a sweepable substantiallyinertialess cathode ray beam, thus providing a minimum attack and decaytime.

Another feature relates to an instantaneous type compressor or to aninstantaneous type expander wherein the desired compressing or expandingfunction is controlled by a sweepable cathode ray beam and a speciallydesigned electron mask which forms part of the cathode ray tube. Themask is so designed with respect to the shape and sweeping action of thecathode ray beam so as to impart directly to the output of the cathoderay tube the desired signal compression or signal expansion.

A further feature relates to a novel instantaneous compandor for PTMsignals employing as the compandor control a novel construction ofcathode ray tube.

A still further feature relates to the novel method of compressing orexpanding the time deviation of pulse time modulation pulses by storingthe pulse time modulation pulses on a storage surface in a predeterminedgraph- 1 2,959,641 Patented Nov. 8, 1960 like configuration or array ofelemental storage areas, and then electronically reading the storedpulse time modulation pulses to produce a PTM signal output having thedesired compression or expansion.

An additional feature relates to the employment of the novel cathode raytube mentioned above as an instantaneous type compressor or aninstantaneous type expander for a multichannel PTM pulse train appliedthereto.

. Other features and advantages will appear from the ensuingdescriptions, the appended claims, and the attached drawing.

In the drawing, which shows by way of example one preferred embodiment,

Fig. l is a schematic block diagram of a PTM system embodying thecompressor and expander units according to the invention;

Fig. 2 is a schematic diagram of the cathode ray tube compressor orexpander according to the invention;

Fig. 3 is a face view of the compressor mask shown in edge view in Fig.2;

Fig. 4 shows a series of graphs used in explaining the operation of theinvention; and

I Fig. 5 is a face view of the mask when the device of Fig. 2 is used asan expander.

Referring to Fig. 1, there is disclosed therein a multichannelcommunication system employing a compressor and. an expander inaccordance with the invention. The multiplexer end of the systemincludes a plurality of PTM modulators 1 of any well-known kind, suchfor example as described in U.S. Patent 2,485,591. Each modulatorproduces a series of pulses representing by their time position theamplitude of the signals of modulating sources 2. The outputs ofmodulators 1 are coupled to a common point 3 for multiplexing into a PTMpulse train. The time of occurrence of each channel PTM pulse isdetermined by the base frequency generator 4 and the delay line timingdistributor 5. The generator 4 also times the production of asynchronizing or marker pulse repetitious at the frequency of the outputof generator 4. Thus, at point 3 the channel PTM pulses are interleavedin time between successive marker pulses to produce a plurality of pulsetrains repetitious at the frequency of generator 4. The PTM pulses ofeach signal channel occupy a given time of the pulse train. This giventime is the maximum time deviation of the PTM pulses, said maximum timedeviation being proportional to the maximum amplitude of the modulatingsignal. A guard time can be provided between adjacent channels. The PTMpulse trains are then impressed upon a compressor unit 6 according tothe invention, and to be described in connection with Figs. 2-4. For thepresent, suflice it to say that the unit 6 maintains the time deviationof the pulse time modulation pulses at its output within a predeterminedtime deviation proportional to a given volume range. Thus the generalcharacteristic of the compressor 6 has to be such that most of the time'deviations proportional'to modulating signal amplitude are concentratedin the early part of the pulse time modulation pulse time deviations.One way of doing this is to decrease the time deviations of thesuccessive sample d amplitudes of the modulating signal in a such a waythat the successive decreased time deviations follow a predeterminedcharacteristic. The curve relating instantaneous input signal timedeviation to instantaneous output time deviation of the compressor maybe according to any pre-' determined characteristic;suchfor example asthat repre sented by the graph 7. The pulses which have had their timedeviations compressed are then transmitted over any suitable radiofrequency link transmitter 8 of known design, and then impressed uponthe transmitting antenna 9.

The signals are picked up by a suitable receiving antenna 10 and areimpressed upon any well-known radio receiver 11 for detecting the timedeviations of the pulse time modulation pulses. These pulse timemodulation pulses are then passed through an expander 12 which has acharacteristic 13 relating instantaneous input time deviation toinstantaneous output time deviation, which characteristic iscomplementary or inverse to the characteristic 7 of the compressor. Inother words, the characteristic curve 13 may be considered the same asthe characteristic curve 7 but rotated through 180, the axis of rotationbeing the straight portions of the curves.

The PTM pulse train with pulses, the time deviation of which has beenexpanded is then coupled to a plurality of any well-known demodulators14. Demodulators 14 under control of the timing pulses of delay linedistributor 15 separates its corresponding channel pulse from the pulsetrain and converts the PTM pulses into intelligence signals. Thisoperation is described in said US. Patent 2,485,591 and gives an exampleof one type of demodulator that may be employed in conjunction with mynovel compandor. The outputs of demodulators 14 are coupled to theirrespective channel loads 16.

The timing of the outputs of distributor 15 is synchronized with thetransmitter base frequency generator 4 by the synchronizing or markersignal. This marker signal is detected in marker separator 17 whichsupplies a synchronized signal to distributor 15 for the appropriatetimed distribution to the demodulators 14.

Referring to Figs. 2-4, a description will now be given of thecompressor unit 6. Since the expander unit 12 is of the sameconstruction as the unit 6, it will only be necessary to explain indetail the construction and operation of the compressor unit. In generalthe unit 6 comprises the cathode ray tube 22 (see Fig. 2) having theusual evacuated enclosing bulb 23 with any well known electron gun 24located at one end thereof. Mounted in relatively closely spacedrelation to the gun is the control grid 25 upon which the PTM signalsare impressed. Located in the path of the electrons passed by grid 25 isa pair of spaced plates 26, 27 which extend parallel to each other andto the plane of the sheet of drawing. These plates are connected to asuitable direct current potential source (not shown) so as to form theelectron stream from the gun into a sheet-like beam, the plane of whichis parallel to the sheet of the drawing. In front of the sheet-formingplates are the usual beam deflecting plates 28, 29 which can beconnected to any well-known source of sweep voltage 30 for deflectingthe sheet beam in a direction perpendicular to the plane of the drawing,which direction for convenience of description will be referred toherein as the X direction.

Mounted in front of the plates 28, 29 is an apertured electron mask 31which may be a metal plate having an electron transparent slit 32 of acontour which is the same as or bears a definite configurationalrelation to the above-mentioned characteristic curve 7. In order to showthe relation between the sheet-like electron beam and the slit 32, thebeam is represented in Fig. 3 by the dotted cross-sectional outline 33,and for convenience of description will be referred to as the recordingbeam. Preferably the slit 32 has a substantially linear central region34 terminating in symmetrical curved end regions 35, 36.

Located in closely spaced parallelism with the mask 31 is a signalstorage plate 37 which may be in the form of a dielectric sheet havingthe surface thereof facing the gun 24 provided with a special secondaryemission w n a a h i e pp sur e prov ded wi h a conductive coating sothat when the beam passes through the slit 32 and strikes the storageplate at any given point, it sets up at that point an electrostaticstorage charge. Since such storage electrodes are well-known in the art,such as in television pickup tubes, electrostatic signal storage cathoderay tubes, and the like, detailed description thereof is not necessaryherein. Suffice it to say that the charge which is localized at anygiven elemental area of the storage surface, as determined by theintersection of the beam 33 and the slit 32, will remain stored at thatelemental area until it is read or discharged by a second sheet-likeelectron beam, referred to as the reading beam.

It will be clear from the foregoing that the beam 33 where it intersectsthe electron-transparent slit 32 scans the storage plate 37 in a linewhich has the same shape as the said slit. Preferably the control grid25 is, in the absence of PTM pulses, biased to plate current cut-01f sothat in the absence of a PTM pulse no corresponding charge is stored onplate 37. However, when the grid 25 is energized by time-spaced PTMpulses, those pulses are stored as electrostatic dots on the plate 37and the array or succession of such dots will be along the path definedby the shape of slit 32.

Located at the opposite end of the tube 22 is another electron gun 38which constitutes the reading gun. It is provided with a pair of spacedplates 39, 40 similar to plates 26, 27 to form the electrons from gun 38into a sheet-like beam. In a general sense it is required only that theplane of beam 41 is not parallel to the plane of beam 33. Preferably,however, the plane of beam 41 is perpendicular to the sheet of thedrawing or in other words lies in the X plane and hence is perpendicularto the plane of beam 33. The reading beam is represented schematicallyin Fig. 3 by the dot-dash crosssectional outline 41 in its preferredform. Located in front of the sheet-forming plates 39, 40 are a pair ofbeam deflecting plates 42, 43 for deflecting beam 41 perpendicular tothe X plane or in other words in the Y direction. The storage plate 37is connected to ground through a suitable resistor 44 which is connectedto the input of a suitable amplifier 45 whose output is connected to thetransmitter 8 (Fig. 1). Therefore, as the beam 41 sweeps across thestored charges on plate 37, it generates pulses corresponding to thelocation of those charges in the given configuration defined by slit 32.Deflection plates 42 and 43 and forming plates 39 and 40 would bedisposed at a given angle to deflection plates 28 and 29 and formingplates 26 and 27 to provide the more general orientation of beams 41 and33.

It should be noted that the beam 41 is continuously On even though thecontrol grid 25 of the recording gun is keyed on only in response to animpressed PTM pulse. Preferably, however, there is a predetermined timedelay D between the recording sweep of beam 33 and the reading sweep ofbeam 41. This relation is shown in the graphs of Fig. 4. In that figurethe sawtooth waves 46 represent the sweep voltage for sweeping therecording beam and the sawtooth waves 47 represent the sweep voltage forthe reading beam timed for operation on one signal channel, the delaybetween the two sweeps being indicated by the designation D Therepetition rate of waves 46 and 47 are equal to the repetition rate ofthe individual channel pulses being operated on. The typical PTM inputpulses for one 'channel are represented by the numerals 48, 49, 50 andthe corresponding PTM output pulses are represented by the numerals 48a,49a, 50a. It will be clear from the foregoing, therefore, that becauseof the slope of the slit 32, and because of the intersectional relationbetween that slit and the reading and recording beams, the timedeviation of successive PTM pulses will be compressed and maintainedwith a predetermined time distribution as determined by the shape of theslit 32.

The waveforms of Fig. 4 are for one channel. It must be remembered thatthe compressor of this invention operates on the time deviation of thechannel pulses of a multi-channel pulse train in sequence. Thus, foreach channel the sweep generators 30 and 51 must be triggered to producea sweep waveform having a repetition frequency equal to the channelrepetition frequency and having a period equal at least to the maximumdeviation of the channel pulse. Preferably the period of the sweepwaveform is slightly greater than the maximum deviation of the channelpulse. The triggering or timing pulses for the compressor and expanderare derived from the channel taps of distriubtors 5 and 15, respectively, as indicated in Fig. l. The timing signals are directly coupledto sweep generator 30 of Fig. 2 and through delay lines 52 to sweepgenerator 51. Thus, these timing signals will trigger the production ofsweep waveforms coincident with the maximum channel deviation of thechannel signals of the multiplex pulse train, thereby enabling thecompressor and expander of this invention to operate thereon.

The expander unit 12 at the receiver is of the same construction as slit32a of unit 6 of the transmitter except that the mask 31a, Fig. 5, inthe expander is complementary to slit 32 of mask 31. The recording beam33a and the reading beam 41a when used in the expander have the samepreferred relationship as beams 33 and 41 of the compressor. In otherrespects the expander unit is identical with the compressor unit. Inview of the inverse or complementary relation between the slit 32 of thecompressor and the slit 32a of the expander, the complementary expansionof the time deviation of the pulse time modulation pulses is obtained atthe output of the unit 12, thus restoring the PTM pulses applied to thedemodulators 14 to their original time deviation relation.

While I have described above the principles of my invention inconnection with specific apparatus, it is to be clearly understood thatthis description is made only by way of example and not as a limitationto the scope of my invention as set forth in the objects thereof and inthe accompanying claims.

What is claimed is:

1. An instantaneous type compressor of the time deviation of pulse timemodulation pulses for pulse time modulation systems and the likecomprising means to store the pulse time modulation pulses on a storagesurface in the form of energy including means in juxtaposition to saidstorage surface to confine the Storage of said energy on said storagesurface in a given configuration correlated with the desired compressionof the time deviation of the pulse time modulation pulse, and means toelectronically scan said stored energy to produce corresponding outputpulse time modulation pulses having the desired time compression.

2. An instantaneous type expander of the time deviation of pulse timemodulation pulses for pulse time modulation systems and the likecomprising means to store the pulse time modulation pulses on a storagesurface in the form of energy including means in juxtaposition to saidstorage surface to confine the storage of said energy on said storagesurface in a given configuration correlated with the desired expansionof the time deviation of the pulse time modulation pulses, and means toelectronically scan said stored energy to produce corresponding outputpulse time modulation pulses having the desired timeexpansion.

3. An instantaneous type compandor combination for pulse time modulationtransmission systems comprising at the transmitter means to store thepulse time modulation pulses on a storage surface in the form of energyincluding means in juxtaposition to said storage surface to confine thestorage of said energy on said storage surface in a first givenconfiguration correlated with the desired compression of the timedeviation of the pulse time modulation pulses, means to electronicallyscan said 6 stored energy to produce corresponding output pulse timemodulation pulses having the desired time compression, and means totransmit said time compressed pulses, and at the receiver means toreceive said time compressed pulses, means to store said time compressedpulses on a storage surface in the form of energy including means injuxtaposition to said storage surface to confine the storage of saidenergy on said storage surface in a second given configurationcomplementary to said first configuration, and means to electronicallyscan said stored energy at said receiver to reproduce the original pulsetime modulation pulses with their original time deviated relations.

4. An instantaneous type compressor of the time deviation of pulse timemodulation pulses for pulse time modulation systems and the likecomprising an electrostatic storage surface, a mask having a slit of apredetermined configuration therethrough correlated with the desiredcompression of the time deviation of the pulse time modulation pulses,said mask being disposed in juxtaposition to said storage surface, meansto record the pulse time modulation pulses as corresponding charges onsaid storage surface through said slit with the successive chargesfollowing the configuration of said slit, and means for electronicallyreading said charges stored on said storage surface to produce outputpulse time modulation pulses having the desired time compression.

5. A compressor according to claim 4, in which means are provided toproduce a predetermined time delay between the recording of said pulsetime modulation pulses and the electronic reading thereof.

6. An instantaneous type expander of the time deviation of pulse timemodulation pulses for pulse time modulation systems and the likecomprising an electrostatic storage. surface, a mask having a slit of apredetermined configuration therethrough correlated with the desiredexpansion of the time deviation of the pulse time modulation pulses,said mask being disposed in juxtaposition to said storage surface, meansto record the pulse time modulation pulses as corresponding charges onsaid storage surface through said slit with the successive chargesfollowing the configuration of said slit, and means for electronicallyreading said charges stored on said storage surface to produce outputpulse time modulation pulses having the desired time expansion.

7. An instantaneous type compandor combination for pulse time modulationtransmission systems comprising at the transmitter a first electronicstorage surface, a first mask having a slit of a predeterminedconfiguration therethrough correlated with the desired compression ofthe time deviation of the pulse time modulation pulses, said first maskbeing disposed in juxtaposition to the first storage surface, means torecord the pulse time modulation pulses to be transmitted ascorresponding charges on said first storage surface through said slit insaid first mask with the successive charges following the configurationof said slit, means for electronically reading said charges on saidfirst storage surface to produce output pulse time modulation pulseswith the desired time compression, means coupled to said reading meansto transmit said compressed pulse time modulation pulses, and at thereceiver means to receive said compressed pulse time modulation pulses,a second electrostatic storage surface, a second mask having a slit ofpredetermined configuration therethrough correlated with the requiredexpansion of the time deviation of the pulse time modulation pulses tobe complementary to the compression of the time deviation of the pulsetime modulation pulses, said second mask being disposed in juxtapositionto said second storage surface, means to record said compressed pulsetime modulation pulses as corresponding charges on said second mask withthe successive charges following the configuration of said slit of saidsecond mask, and means for electronically reading said charges on saidsecond storage surface to produce pulse time modulation pulses having.

7 the same time deviation as the pulse time modulation pulses prior totime compression.

8. An instantaneous type compandor device for pulse time modulationsystems and the like comprising a cathode ray tube having a firstelectron gun, a control grid for said gun upon which pulse timemodulation pulses for transmission are impressed, means to shape thecontrolled electron stream from said gun into a sheet-like beam, meansto deflect said sheet-like beam into a direction perpendicular to theplane of said beam, an electrostatic storage surface upon which the beamimpinges, a mask in the path of said beam before it impinges on saidsurface, said mask having an electron transparent slit of apredetermined configuration correlated with the desired compression ofthe time deviation of the pulse time modulation pulses, and anotherelectron gun for reading the stored charges on said surface in timedelay relation to the recording thereof.

9. A compandor device according to claim 8, in which the said otherelectron gun is provided with means for forming the electron beamtherefrom into a sheet-like beam in a plane substantially perpendicularto the first mentioned beam, and means for deflecting the sheet-likebeam from said other gun in a direction perpendicular to the planethereof.

10. An instantaneous type device for varying the time deviation of pulsetime modulation pulses in pulse time modulation systems and the likecomprising a cathode ray tube having means to develop a recordingcathode ray beam of sheet-like shape, means to deflect said beam in adirection normal to the cross-sectional length of the beam, anelectrostatic storage surface, an apertured electron mask locatedbetween said deflecting means and said surface, said mask having anelectron transparent portion defining a configurational shape correlatedwith the desired time deviation of pulse time modulation pulses wherebythe scanning thereof by said recording beam produces storedelectrostatic dots on said surface along said electron transparentportion, and electronic means to read said stored dots to produce acorresponding series of output pulse time modulation signals having thedesired time deviated relations.

11. A device according to claim 10, in which the means to develop saidrecording beam comprises an electron gun having means to scan saidsurface in an X direction, and the means for electronically reading saidstored dots comprises another electron gun having means to scan saidsurface in a Y direction.

12. An instantaneous type compandor for pulse transmission systemscomprising a compressor of the time deviation of pulse time modulationpulses including a first cathode ray tube having a first electron gunand a second electron gun, means to form the beam from the first guninto a sheet-like beam for recording, means for forming the beam fromthe second gun into a sheet-like beam for reading, the planes of saidsheet-like beams being mutually perpendicular, an electrostaticrecording plate having a recording surface located between said guns,means to sweep the first sheet-like beam in one direction across saidsurface, means to sweep the second sheet-like beam across said surfacein a direction perpendicular to that of the first beam, a control gridfor keying the first beam on and off by the pulses the time deviation ofwhich is to be compressed, an electron permeable mask between the firstgun and said surface, said mask having an aperture which is electrontransparent and'having a configuration which is correlated with thedesired time compression characteristic, and a pulse expander forreceiving the time compressed pulses, said expander having a timeexpansion characteristic complementary to the time compressioncharacteristic of the compressor, said expander having a cathode raytube substantially the same as said first cathode ray tube and includinga similar electron transparent mask but with the aperture thereoforiented with respect to its associated recording and reading beams 7nals in a direction normal to the crosssectional length of the beam, anelectrostatic storage surface, an apertured electron mask locatedbetween said deflecting means and said surface, said mask having anelectron transparent portion defining a configurational shape correlatedwith the desired signal compression whereby the scanning thereof by saidrecording beam produces stored electrostatic dots on said surface alongsaid electron transparent portion, and electronic means in synchronismwith each or" said channel signals to read said stored dots to produce acorresponding series of output pulse time modulation signals having thedesired signal compression.

14. An instantaneous type time expander for multichannel pulse timemodulation signals having a synchronizing signal and a plurality ofchannel signals comprising a cathode ray tube having means to develop arecording cathode ray beam of sheet-like shape, means to deflect saidbeam in synchronism with each of said channel signals in a directionnormal to the cross-sectional length of the beam, an electrostaticstorage surface, an apertured electron mask located between saiddeflecting means and said surface, said mask having an electrontransparent portion defining a configurational shape correlated with thedesired signal expansion whereby the scanning there of by said recordingbeam produces stored electrostatic dots on said surface along saidelectron transparent portion, and electronic means in synchronism witheach of said channel signals to read said stored dots toproduce acorresponding series of output pulse time modulation signals having thedesired signal expansion.

15. An instantaneous type compandor for multichannel pulse timemodulation transmission systems wherein the intelligence is carried by apulse train having a synchronizing signal and a plurality of signalchannels comprising a compressor of the time deviation of pulse timemodulation pulses including a first cathode ray tube having a firstelectron gun and a second electron gun, means to form the beam from thefirst gun into a sheetlike beam for recording, means for forming thebeam from the second gun into a sheet-like beam for reading, the planesof said sheet-like beams being mutually perpendicular, an electrostaticrecording plate having a recording surface located between said guns,means to sweep the first sheet-like beam in one direction across saidsurface in synchronism with each of saidsignal channels, means to sweepthe second sheet-like beam across said surface in a directionperpendicular to that of said first beam in synchronism with each ofsaid signal channels, means to delay the initiation of the sweep of saidsecond beam with respect to said first beam, a control grid for keyingthe first beam on and off by the pulses the time deviationof which is tobe compressed, an electron permeable mask between the first gun and saidsurface, said mask having an aperture which is electron transparent andhaving a configuration which is correlated with the desired timecompression characteristic, and an expander of the time deviation ofpulse time modulation pulses for receiving the time compressed pulsesincluding a second cathode ray tube having a third electron gun and afourth electron gun, means to form the beam from the third gun into asheet-like beam for recording, means for forming the beam from thefourth gun into a sheetlike beam for reading, the planes of saidsheet-like beams being mutually perpendicular, an electrostaticrecording plate having a recording surface located between said guns,means to sweep the third sheet-like beam in one direction across saidsurface in synchronism with each of said signal channels, means to sweepthe fourth sheet-like beam across said surface in a directionperpendicular to that of said third beam in synchronism with each ofsaid signal channels, means to delay the initiation of the sweep of saidfourth beam with respect to said third beam, a control grid for keyingthe third beam on and off by the pulses the time deviation of which isto be expanded, an electron permeable mask between the third gun andsaid surface, said mask having an aperture which is electron transparentand having a configuration which is correlated with a time expansioncharacteristic complementary to the time compression characteristic ofsaid compressor.

References Cited in the file of this patent UNITED STATES PATENTSHartley Feb. 13, 1940 Riesz Oct. 22, 1940 Labin et a1. Aug. 1, 1950Anderson et a1 Feb. 24, 1953 Von Sivers et a1. Oct. 23, 1956 Levine June11, 1957

